US3707718A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Radar system
Assignee: Westinghouse Electric Corp
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Filing: 1969-02-18
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Granted: 1972-12-26
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Expires: 1989-02-18
Abstract
Abstract There is disclosed a pulse-doppler, moving-target, air-borne, radar with a plurality of range-gating channels and a novel clutter tracker for suppressing, from the intelligence correlated to obtain range and velocity, the clutter reflected from ground. The clutter is suppressed by filters and the frequency of the clutter is maintained within the notch of the filters by an AFC. The mixer of this AFC which sets this notch frequency is driven from an oscillator whose frequency is set in dependence upon the frequency of the clutter signal without confusion (centroiding) from large target signals near in frequency to the clutter signal. The clutter signal is isolated from the confusing target signals by reliance on the phenomenon that the clutter alone passes through most of the range channels and may be detected by a gate which responds to the simultaneous passage of signals through this plurality of range channels.
Inventors
- 👤 Stephen A Ames
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 03:17
CPC Classifications
G; G01; G01S; G01S13/00; G01S13/02; G01S13/50; G01S13/52; G01S13/522; G01S13/524; G01S13/53; G01S13/58; G01S13/64
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
232 words
A pulsed-doppler moving-target radar system including means for transmitting pulses of RF signals to a region under observation, said region including, in addition to targets, which reflect target signals, the ground which reflects clutter signals, a receiver including a first mixer and an IF amplifier and a plurality of signal channels connected to the output of said amplifier each having a range gate through which said clutter signals and target signals are passed selectively into the respective channels during successive range-gate cycles, each of said channels also having connected in cascade with said respective range gates, wide bandpass filters, second mixers, clutter band rejection filters, doppler frequency output means, a clutter tracker unit having respective means connected to the outputs of each of the respective second mixers for maintaining the derived frequency band of the signals of the respective channels, including the doppler frequency, within the frequency band of said rejection filters, means for intermittently opening and closing said gates sequentially during sub-intervals of the time intervals between said R.F. pulses to thereby selectively separate target signals from the clutter on the basis of range and doppler frequency, a voltage controlled oscillator for supplying a sweeping heterodyne frequency to said second mixers and responsive to the clutter frequency in a plurality of said channels for maintaining the derived frequency of the clutter signal within the frequency band of said clutter rejection filters.
Claim 2
Dependent Claim
232 words
A pulsed-doppler moving-target radar system including means for transmitting pulses of RF signals to a region under observation, said region including, in addition to targets, which reflect target signals, the ground which reflects clutter signals, a receiver including a first mixer and an IF amplifier and a plurality of signal channels connected to the output of said amplifier each having a range gate through which said clutter signals and target signals are passed selectively into the respective channels during successive range-gate cycles, each of said channels also having connected in cascade with said respective range gates, wide bandpass filters, second mixers, clutter band rejection filters, doppler frequency output means, a clutter tracker unit having respective means connected to the outputs of each of the respective second mixers for maintaining the derived frequency band of the signals of the respective channels, including the doppler frequency, within the frequency band of said rejection filters, means for intermittently opening and closing said gates sequentially during sub-intervals of the time intervals between said R.F. pulses to thereby selectively separate target signals from the clutter on the basis of range and doppler frequency, a voltage controlled oscillator for supplying a sweeping heterodyne frequency to said second mixers and responsive to the clutter frequency in a plurality of said channels for maintaining the derived frequency of the clutter signal within the frequency band of said clutter rejection filters.
Claim 3
Dependent Claim
27 words
The system of claim 1 wherein the clutter tracker is not responsive to the passing of target signals by substantially less than the plurality of the gates.
Claim 4
Dependent Claim
51 words
The receiver of claim 1 wherein the clutter-tracking means includes a spectrum analyzer and also includes normally-closed gating means connected to receive the output of said analyzer, said gating means opening only responsive to the simultaneous passage by said analyzer of signals for at least a plurality of the range channels.
Claim 5
Dependent Claim
58 words
The pulsed-doppler moving-target radar system as set forth in claim 1 in which said clutter tracker unit includes a threshold circuit in each of said frequency deriving means and a majority gate responsive to a signal exceeding a threshold magnitude passed simultaneously by the majority of said mixers to determine the deviation, if any, of the clutter signal.
Claim 6
Dependent Claim
36 words
The receiver of claim 4 wherein said voltage-controlled oscillator is controlled by means including means for maintaining the control of the oscillator independent of the width, as a function of frequency, of the received clutter pulse.
Claim 7
Dependent Claim
57 words
The receiver of claim 4 wherein the controlling means includes means for deriving a controlling signal having a frequency corresponding to the center frequency of the clutter signal as it is received by said receiver, the oscillator being controlled by the deviation of the frequency of said controlled signal from the frequency corresponding to tHe maintained frequency.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-12-26 | 1976-06-26 | 1976-12-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-12-26 | 1980-06-26 | 1980-12-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-12-26 | 1984-06-26 | 1984-12-26 | $7700.00 | Window Closed / Lapsed |